ProteinNEW2026-08

Synergistic effects of synbiotic, protein supplementation, and resistance training on inflammation, oxidative stress, and muscle strength in older adults with type 2 diabetes mellitus: a RCT triple-blinded study.

Bastos Marta Ferreira, Longo Priscila Larcher, Furtado Guilherme Eustáquio, Dos Santos Joselma Rodrigues et al. — European journal of nutrition

Summary

A study investigated how protein supplements and resistance training affect older adults with type 2 diabetes. It found that combining protein with exercise improved muscle strength, physical abilities, and some health markers. Adding a synbiotic supplement did not provide extra benefits beyond protein and exercise alone in this group.

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Key points

Older adults with type 2 diabetes can benefit from protein supplements combined with resistance training.
This combination improved muscle strength, physical performance, and insulin sensitivity.
It also positively affected some markers related to oxidative stress.
Adding a synbiotic supplement did not show additional benefits in this study.

What the study looked at

What the study asked: Researchers wanted to understand if combining protein supplements, a synbiotic (probiotics + prebiotics), and resistance exercise could help older adults with type 2 diabetes improve their muscle strength, reduce inflammation, and combat oxidative stress. This is important because aging, diabetes, and factors like low protein intake can worsen these health issues. How it was studied: This was a randomized, triple-blinded clinical trial involving men aged 65 and older who had type 2 diabetes. Participants were divided into three groups: a control group, a group receiving protein supplements, and another group receiving both synbiotic and protein supplements. All groups participated in a resistance training program. This design helps ensure that any observed effects are due to the interventions rather than other factors. What it found: The study found that all participants, regardless of their supplement group, showed some improvements in physical performance. However, the groups receiving protein supplementation, especially when combined with resistance training, experienced greater gains in muscle strength, better insulin sensitivity, and reduced markers of oxidative damage. Notably, adding the synbiotic supplement did not provide additional benefits beyond what was achieved with protein and exercise alone.

Dietary takeaway

For older adults, especially those with type 2 diabetes, ensuring adequate protein intake alongside regular resistance training appears beneficial for maintaining and improving muscle strength and overall physical health. While protein supplements can be a convenient way to boost intake, whole food sources like lean meats, fish, eggs, dairy, and legumes are also excellent choices. Remember, this is one study, and more research is always needed to confirm these findings.

Abstract

BACKGROUND: Population aging poses major challenges for the management of type 2 diabetes mellitus (T2DM), particularly because inadequate protein intake, physical inactivity, and gut microbial dysbiosis may contribute to systemic oxidative stress and chronic low-grade inflammation (inflammaging). The present study investigated the combined effects of protein supplementation (P), synbiotic plus protein supplementation (SP), and resistance training (RT) on physical performance, body composition, glycemic control, inflammatory and oxidative stress parameters in older adults with T2DM. METHODS: This randomized, triple-blinded clinical trial included men aged ≥ 65 years with T2DM. Fifty-one participants were randomly allocated to one of three intervention groups: Control (n = 17), Protein (P; n = 17), or Synbiotic + Protein (SP; n = 17). Following withdrawals and losses to follow-up, 40 participants completed the intervention and were included in the final analyses (Control, n = 13; P, n = 13; SP, n = 14). RESULTS: All groups showed improvements in physical performance and an enhanced redox balance, as indicated by higher uric acid levels (an endogenous antioxidant) and lower plasma iron concentrations. Although all groups exhibited increased activities of the muscle damage markers lactate dehydrogenase and creatine kinase, the Protein group demonstrated greater improvements in muscle strength, reduced insulin resistance, and lower oxidative damage associated with heme-iron species. Furthermore, the pro-inflammatory cytokines IFN-γ and IL-6 were elevated in the Protein group, which may reflect their physiological role in exercise-induced metabolic adaptation and energy homeostasis rather than a detrimental inflammatory response. CONCLUSIONS: Protein supplementation combined with RT was associated with improvements in muscle strength, physical performance, insulin resistance, and selected biomarkers of oxidative stress. Under the conditions of the present study, the addition of synbiotic supplementation did not provide further benefits beyond those achieved with protein supplementation and resistance training alone.

View on PubMed →DOI: 10.1007/s00394-026-04076-7